Polynucleotides encoding motilin homologs

ABSTRACT

The present invention is directed to polynucleotides, polypeptides and peptide fragments thereof, and uses thereof for a novel cDNA sequence which has homology to motilin. Tissue distribution of the mRNA for the novel polypeptide is specific to the stomach, small intestine and pancreas. The present invention further includes agonists, antagonists, antibodies, host cells expressing the cDNA encoding the novel motilin homologs and methods for increasing gastric motility using the novel molecules.

This is a divisional application of application Ser. No. 09/046,479,filed Mar. 23, 1998 now U.S. Pat. No. 6,291,653.

REFERENCE TO RELATED APPLICATIONS

This application is related to Provisional Application 60/041,102, filedon Mar. 24, 1997. Under 35 U.S.C. § 119(e) (1), this application claimsbenefit of said Provisional Application.

BACKGROUND OF THE INVENTION

Many of the regulatory peptides that are important in maintainingnutritional homeostasis are found in the gastrointestinal environment.These peptides may be synthesized in the digestive system and actlocally, but can also be identified in the brain as well. In addition,the reverse is also found, i.e., peptides are synthesized in the brain,but found to regulate cells in the gastrointestinal tract. Thisphenomena has been called the “brain-gut axis” and is important forsignaling satiety, regulating body temperature and other physiologicalprocesses that require feedback between the brain and gut.

The gut peptide hormones include gastrin, cholecystokinin (CCK),secretin, gastric inhibitory peptide (GIP), vasoactive intestinalpolypeptide (VIP), motilin, somatostatin, pancreatic peptide (PP),substance P and neuropeptide Y (NPY), and use several differentmechanisms of action. For example, gastrin, motilin and CCK function asendocrine- and neurocrine-type hormones. Others, such as gastrin andGIP, are thought to act exclusively in an endocrine fashion. Other modesof action include a combination of endocrine, neurocrine and paracrineaction (somatostatin); exclusively neurocrine action (NPY); and acombination of neurocrine and paracrine actions (VIP and Substance P).Most of the gut hormone actions are mediated by membrane-bound receptorsand activate second messenger systems. For a review of gut peptides see,Mulvihill et al., in Basic and Clinical Endocrinology, pp. 551-570, 4thedition Greenspan F. S. and Baxter, J. D. editors., Appleton & Lange:Norwalk, Conn., 1994.

Many of these gut peptides are synthesized as inactive precursormolecules that require multiple peptide cleavages to be activated. Thefamily known as the “glucagon-secretin” family which includes VIP,gastrin, secretin, motilin, glucagon and galanin exemplifies peptidesregulated by multiple cleavages and post-translational modifications.

Motilin is a 22 amino acid peptide found in gut tissue of mammalianspecies (Domschke, W., Digestive Diseases 22(5):454-461, 1977). The DNAand amino acid sequences for porcine prepromotilin have been identified(U.S. Pat. No. 5,006,469). Motilin has been identified as a factorcapable of increasing gastric motility, affecting the secretory functionof the stomach by stimulating pepsin secretion (Brown et al., CanadianJ. of Physiol. Pharmacol. 49:399-405, 1971), and recent evidencesuggests a role in myoelectric regulation of stomach and smallintestine. Cyclic increases of motilin have been correlated with phaseIII of the interdigestive myoelectric complex and the hunger contractionof the duodenum (Chey et al., in Gut Hormones, (eds.) Bloom, S. R., pp.355-358, Edinburgh, Churchill Livingstone, 1978; Lee et al, Am. J.Digestive Diseases, 23:789-795, 1978; and Itoh et al., Am. J. DigestiveDiseases, 23:929-935, 1978). Motilin and analogues of motilin have beendemonstrated to produce contraction of gastrointestinal smooth muscle,but not other types of smooth muscle cells (Strunz et al.,Gastroenterology 68:1485-1491, 1975).

The present invention is directed to a novel secreted protein withhomology to motilin, found to be transcribed in the gastrointestinalsystem. The discovery of this novel peptide is important for furtherelucidation of the how the body maintains its nutritional homeostasisand development of therapeutics to intervene in those processes, as wellas other uses that will be apparent from the teachings therein.

SUMMARY OF THE INVENTION

Within one aspect, the present invention provides an isolatedpolynucleotide molecule encoding a polypeptide selected from the groupconsisting of: (a) polynucleotide molecules comprising a nucleotidesequence as shown in SEQ ID NO: 1 from nucleotide 70 to nucleotide 111;(b) allelic variants of (a); (c) orthologs of (a) and (b); and (d)degenerate nucleotide sequences of (a), (b) or (c).

Within another aspect, the present invention provides an isolatedpolypeptide selected from the group consisting of: (a) polypeptidemolecules comprising an amino acid sequence as shown in SEQ ID NO: 2from residue 24 to residue 37; (b) allelic variants of (a); and (c)orthologs of (a) or (b).

In another aspect, the present invention provides an expression vectorcomprising the following operably linked elements: a transcriptionpromoter; a DNA segment selected from the group consisting of: (a)polynucleotide molecules comprising a nucleotide sequence as shown inSEQ ID NO: 1 from nucleotide 70 to nucleotide 111; (b) allelic variantsof (a); (c) orthologs of (a) or (b); and (d) degenerate nucleotidesequences of (a), (b) or (c); a transcription terminator.

In another aspect, the present invention provides a cultured cell intowhich has been introduced an expression vector comprising the followingoperably linked elements: a transcription promoter; a DNA segmentselected from the group consisting of: (a) polynucleotide moleculescomprising a nucleotide sequence as shown in SEQ ID NO: 1 fromnucleotide 70 to nucleotide 111; (b) allelic variants of (a); (c)orthologs of (a) or (b); and (d) degenerate nucleotide sequences of (a),(b) or (c); a transcription terminator, wherein said cell expresses thepolypeptide encoded by the DNA segment.

In another aspect, the present invention provides a pharmaceuticalcomposition comprising purified polypeptide selected from the groupconsisting of: (a) polypeptide molecules comprising an amino acidsequence as shown in SEQ ID NO: 2 from residue 24 to residue 37; (b)allelic variants of (a); and (c) orthologs of (a) or (b), in combinationwith a pharmaceutically acceptable vehicle.

In another aspect, the present invention provides an antibody that bindsto an epitope of a polypeptide selected from the group consisting of:(a) polypeptide molecules comprising an amino acid sequence as shown inSEQ ID NO: 2 from residue 24 to residue 117; (b) allelic variants of(a); and (c) orthologs of (a) or (b).

In another aspect, the present invention provides a method of producinga zsig33 polypeptide comprising: culturing a cell into which has beenintroduced an expression vector comprising the following operably linkedelements: a transcription promoter; a DNA segment selected from thegroup consisting of: (a) polynucleotide molecules comprising anucleotide sequence as shown in SEQ ID NO: 1 from nucleotide 70 tonucleotide 111; (b) allelic variants of (a); (c) orthologs of (a) or(b); and (d) degenerate nucleotide sequences of (a), (b) or (c); atranscription terminator, whereby said cell expresses a polypeptideencoded by the DNA segment; and recovering the polypeptide.

In another aspect, the present invention provides a method ofstimulating gastric motility comprising administering to a mammal inneed thereof, an amount of a composition comprising an isolatedpolypeptide selected from the group consisting of: (a) polypeptidemolecules comprising an amino acid sequence as shown in SEQ ID NO: 2from residue 24 to residue 37; (b) allelic variants of (a); and (c)orthologs of (a) or (b); in a pharmaceutically acceptable vehicle,sufficient to increase transit time or gastric emptying of an ingestedsubstance.

DETAILED DESCRIPTION OF THE INVENTION

Prior to describing the present invention in detail, it may be helpfulto define certain terms used herein:

The term “ortholog” denotes a polypeptide or protein obtained from onespecies that is the functional counterpart of a polypeptide or proteinfrom a different species. Sequence differences among orthologs are theresult of speciation.

“Paralogs” are distinct but structurally related proteins made by anorganism. Paralogs are believed to arise through gene duplication. Forexample, α-globin, β-globin, and myoglobin are paralogs of each other.

The term “allelic variant” denotes any of two or more alternative formsof a gene occupying the same chromosomal locus. Allelic variation arisesnaturally through mutation, and may result in phenotypic polymorphismwithin populations. Gene mutations can be silent (no change in theencoded polypeptide) or may encode polypeptides having altered aminoacid sequence. The term allelic variant is also used herein to denote aprotein encoded by an allelic variant of a gene.

The term “expression vector” denotes a DNA molecule, linear or circular,that comprises a segment encoding a polypeptide of interest operablylinked to additional segments that provide for its transcription. Suchadditional segments may include promoter and terminator sequences, andmay optionally include one or more origins of replication, one or moreselectable markers, an enhancer, a polyadenylation signal, and the like.Expression vectors are generally derived from plasmid or viral DNA, ormay contain elements of both.

The term “isolated”, when applied to a polynucleotide molecule, denotesthat the polynucleotide has been removed from its natural genetic milieuand is thus free of other extraneous or unwanted coding sequences, andis in a form suitable for use within genetically engineered proteinproduction systems. Such isolated molecules are those that are separatedfrom their natural environment and include cDNA and genomic clones.Isolated DNA molecules of the present invention are free of other geneswith which they are ordinarily associated, but may include naturallyoccurring 5′ and 3′ untranslated regions such as promoters andterminators. The identification of associated regions will be evident toone of ordinary skill in the art (see for example, Dynan and Tijan,Nature 316:774-78, 1985). When applied to a protein, the term “isolated”indicates that the protein is found in a condition other than its nativeenvironment, such as apart from blood and animal tissue. In a preferredform, the isolated protein is substantially free of other proteins,particularly other proteins of animal origin. It is preferred to providethe protein in a highly purified form, i.e., greater than 95% pure, morepreferably greater than 99% pure.

The term “operably linked”, when referring to DNA segments, denotes thatthe segments are arranged so that they function in concert for theirintended purposes, e.g. transcription initiates in the promoter andproceeds through the coding segment to the terminator,

The term “polynucleotide” denotes a single- or double-stranded polymerof deoxyribonucleotide or ribonucleotide bases read from the 5′ to the3′ end. Polynucleotides include RNA and DNA, and may be isolated fromnatural sources, synthesized in vitro, or prepared from a combination ofnatural and synthetic molecules.

The term “complements of polynucleotide molecules” denotespolynucleotide molecules having a complementary base sequence andreverse orientation as compared to a reference sequence. For example,the sequence 5′ ATGCACGGG 3′ is complementary to 5′ CCCGTGCAT 3′.

The term “degenerate nucleotide sequence” denotes a sequence ofnucleotides that includes one or more degenerate codons (as compared toa reference polynucleotide molecule that encodes a polypeptide).Degenerate codons contain different triplets of nucleotides, but encodethe same amino acid residue (i.e., GAU and GAC triplets each encodeAsp).

The term “promoter” denotes a portion of a gene containing DNA sequencesthat provide for the binding of RNA polymerase and initiation oftranscription. Promoter sequences are commonly, but not always, found inthe 5′ non-coding regions of genes.

The term “secretory signal sequence” denotes a DNA sequence that encodesa polypeptide (a “secretory peptide”) that, as a component of a largerpolypeptide, directs the larger polypeptide through a secretory pathwayof a cell in which it is synthesized. The larger peptide is commonlycleaved to remove the secretory peptide during transit through thesecretory pathway.

The term “receptor” denotes a cell-associated protein that binds to abioactive molecule (i.e., a ligand) and mediates the effect of theligand on the cell. Membrane-bound receptors are characterized by amulti-domain structure comprising an extracellular ligand-binding domainand an intracellular effector domain that is typically involved insignal transduction. Binding of ligand to receptor results in aconformational change in the receptor that causes an interaction betweenthe effector domain and other molecule(s) in the cell. This interactionin turn leads to an alteration in the metabolism of the cell. Metabolicevents that are linked to receptor-ligand interactions include genetranscription, phosphorylation, dephosphorylation, increases in cyclicAMP production, mobilization of cellular calcium, mobilization ofmembrane lipids, cell adhesion, hydrolysis of inositol lipids andhydrolysis of phospholipids. Most nuclear receptors also exhibit amulti-domain structure, including an amino-terminal, transactivatingdomain, a DNA binding domain and a ligand binding domain. In general,receptors can be membrane bound, cytosolic or nuclear; monomeric (e.g.,thyroid stimulating hormone receptor, beta-adrenergic receptor) ormultimeric (e.g., PDGF receptor, growth hormone receptor, IL-3 receptor,GM-CSF receptor, G-CSF receptor, erythropoietin receptor and IL-6receptor).

The term “complement/anti-complement pair” denotes non-identicalmoieties that form a non-covalently associated, stable pair underappropriate conditions. For instance, biotin and avidin (orstreptavidin) are prototypical members of a complement/anti-complementpair. Other exemplary complement/anti-complement pairs includereceptor/ligand pairs, antibody/antigen (or hapten or epitope) pairs,sense/antisense polynucleotide pairs, and the like. Where subsequentdissociation of the complement/anti-complement pair is desirable, thecomplement/anti-complement pair preferably has a binding affinity of<10⁹ M^(—1).

All references cited herein are incorporated by reference in theirentirety.

The present invention is based in part upon the discovery of a novelhuman DNA sequence that encodes a novel secreted polypeptide havinghomology to motilin, of which the closest homolog is porcine motilin(shown in SEQ ID NOs: 3 and 4). Motilin is member of a family ofpolypeptides that regulate the gastrointestinal physiology. The familyof polypeptides important in gastrointestinal regulation to whichmotilin belongs includes glucagon, gastrin, galanin, and vasoactiveintestinal peptide (VIP). These polypeptides are synthesized in aprecursor form that requires multiple steps of processing to the activeform. Particularly relevant to the polypeptide of the present inventionare motilin, VIP and galanin, where processing involves removal ofsignal sequence, followed by cleavage of one or more accessory peptidesto release the active peptide. The resulting active peptide is generallysmall (10-30 amino acids) and may require further post-translationalmodifications, such as amidation, sulfation or pyrrolidan carbonylicacid modification of glutamic residues.

Analysis of the tissue distribution of the mRNA corresponding to thisnovel DNA showed that expression was highest in stomach, followed byapparent but decreased expression levels in small intestine andpancreas. The EST is also present in lung cDNA libraries. Thepolypeptide has been designated zsig33.

The novel zsig33 polynucleotides and polypeptides of the presentinvention were initially identified by querying an EST database forsequences possessing a putative secretion signal. An EST sequence wasdiscovered and predicted to be related to the motilin family. The ESTsequence was derived from a fetal pancreatic library.

The novel polypeptide encoded by the full length cDNA is 117 aminoacids. The predicted signal sequence is 23 amino acid residues (aminoacid residues 1 to 23 of SEQ ID NO: 2). The active peptide was predictedto be 18 amino acid residues (amino acid residues 24 to 41 of SEQ ID NO:2), with a C-terminal cleavage after amino acid residue 41 of SEQ ID NO:2 (Ser). However, many of the gut-brain peptides require multiplecleavages. For example, progastrin peptide is 101 amino acids, and iscleaved at the N-terminus resulting in sequentially smaller peptides(G34, G17 and G14) (Sugano et al., J. Biol. Chem. 260:11724-11729,1985). Other peptides that require multiple processing steps includeglucagon, for which C-terminal cleavages result in glucagon-like peptide1 and glucagon-like peptide 2 and galanin, in which processing involvescleavage of a C-terminal peptide known as GMAP. Therefore, an additionalpeptide based on cleavage after amino acid 37 of SEQ ID NO: 2 (Gln) wassynthesized and resulted in a 14 amino acid peptide with biologicalactivity (from amino acid residue 24 (Gly) to amino acid residue 37(Gln) of SEQ ID NO: 2).

The C-terminal peptide (amino acid 42 to 117 of SEQ ID NO: 2) may havesome specialized activity as well. Processing of the active peptide formotilin (shown in SEQ ID NO: 4) results in a release of a C-terminalpeptide of 70 amino acids, amino acid residue 50 (Ser) to amino acidresidue 119 (Lys), known as motilin-associated peptide (MAP). Adelman etal., (U.S. Pat. No. 5,006,469) have postulated that MAP plays a role inregulation of digestion, appetite and nutrient absorption.

The highly conserved amino acids in the polypeptide zsig33 can be usedas a tool to identify new family members. For instance, reversetranscription-polymerase chain reaction (RT-PCR) can be used to amplifysequences encoding the conserved motif from RNA obtained from a varietyof tissue sources. Two such conserved domains have been identified usingsequences from the present invention. The first domain is found at aminoacid residues 31 to 36 of SEQ ID NO: 2, wherein the motif identified isGlu X Gln Arg X Gln, wherein X is any amino acid residue (shown in SEQID NO: 6), and the second domain is found at amino acid residues 78 to84 of SEQ ID NO: 2, wherein the motif identified is Ala Pro X Asp X Glylie, wherein X is any amino acid residue (shown in SEQ ID NO: 7). Inparticular, highly degenerate primers designed from these sequences areuseful for this purpose.

Those skilled in the art will readily recognize that, in view of thedegeneracy of the genetic code, considerable sequence variation ispossible among these polynucleotide molecules encoding SEQ ID NO: 2,including all RNA sequences by substituting U for T. Thus, zsig33polypeptide-encoding polynucleotides and their RNA equivalents arecontemplated by the present invention. Table 1 sets forth the one-lettercodes used to denote degenerate nucleotide positions. “Resolutions” arethe nucleotides denoted by a code letter. “Complement” indicates thecode for the complementary nucleotide(s) For example, the code Y denoteseither C or T, and its complement R denotes A or G, A beingcomplementary to T, and G being complementary to C.

TABLE 1 Nucleotide Resolution Nucleotide Complement A A T T C C G G G GC C T T A A R A|G Y C|T Y C|T R A|G M A|C K G|T K G|T M A|C S C|G S C|GW A|T W A|T H A|C|T D A|G|T B C|G|T V A|C|G V A|C|G B C|G|T O A|G|T HA|C|T N A|C|G|T N A|C|G|T

The degenerate codons encompassing all possible codons for a given aminoacid are set forth in Table 2.

TABLE 2 One Amino Letter Degenerate Acid Code Codons Codon Cys C TGC TGTTGY Ser S AGC AGT TCA TCC TCG TCT WSN Thr T ACA ACC ACG ACT ACN Pro PCCA CCC CCG CCT CCN Ala A GCA GCC GCG GCT GCN Gly G GGA GGC GGG GGT GGNAsn N AAC AAT AAY Asp D GAC GAT GAY Glu E GAA GAG GAR Gln Q CAA CAG CARHis H CAC CAT CAY Arg R AGA AGG CGA CGC CGG CGT MGN Lys K AAA AAG AARMet M ATG ATG Ile I ATA ATC ATT ATH Leu L CTA CTC CTG CTT TTA TTG YTNVal V GTA GTC GTG GTT GTN Phe F TTC TTT TTY Tyr Y TAC TAT TAY Trp W TGGTGG Ter — TAA TAG TGA TRR Asn|Asp B RAY Glu|Gln Z SAR Any X NNN

One of ordinary skill in the art will appreciate that some ambiguity isintroduced in determining a degenerate codon, representative of allpossible codons encoding each amino acid. For example, the degeneratecodon for serine (WSN) can, in some circumstances, encode arginine(AGR), and the degenerate codon for arginine (MGN) can, in somecircumstances, encode serine (AGY). A similar relationship existsbetween codons encoding phenylalanine and leucine. Thus, somepolynucleotides encompassed by the degenerate sequence may encodevariant amino acid sequences, but one of ordinary skill in the art caneasily identify such variant sequences by reference to the amino acidsequence of SEQ ID NO: 2. Variant sequences can be readily tested forfunctionality as described herein.

Within preferred embodiments of the invention the isolatedpolynucleotides will hybridize to similar sized regions of SEQ ID NO: 1,or a sequence complementary thereto, under stringent conditions. Ingeneral, stringent conditions are selected to be about 5° C. lower thanthe thermal melting point (T_(m)) for the specific sequence at a definedionic strength and pH. The T_(m) is the temperature (under defined ionicstrength and pH) at which 50% of the target sequence hybridizes to aperfectly matched probe. Typical stringent conditions are those in whichthe salt concentration is at least about 0.02 M at pH 7 and thetemperature is at least about 60° C.

As previously noted, the isolated polynucleotides of the presentinvention include DNA and RNA. Methods for isolating DNA and RNA arewell known in the art. It is generally preferred to isolate RNA fromstomach, although DNA can also be prepared using RNA from other tissuesor isolated as genomic DNA. Total RNA can be prepared using guanidineHCl extraction followed by isolation by centrifugation in a CsClgradient (Chirgwin et al., Biochemistry 18:52-94, 1979). Poly (A)⁺ RNAis prepared from total RNA using the method of Aviv and Leder (Proc.Natl. Acad. Sci. USA 69:1408-1412, 1972). Complementary DNA (cDNA) isprepared from poly(A)⁺ RNA using known methods. Polynucleotides encodingzsig33 polypeptides are then identified and isolated by, for example,hybridization or PCR.

The present invention further provides counterpart polypeptides andpolynucleotides from other species (orthologs). Of particular interestare zsig33 polypeptides from other mammalian species, including murine,rat, porcine, ovine, bovine, canine, feline, equine and other primateproteins. Orthologs of the human proteins can be cloned usinginformation and compositions provided by the present invention incombination with conventional cloning techniques. For example, a cDNAcan be cloned using mRNA obtained from a tissue or cell type thatexpresses the protein. Suitable sources of mRNA can be identified byprobing Northern blots with probes designed from the sequences disclosedherein. A library is then prepared from mRNA of a positive tissue ofcell line. A zsig33 ortholog-encoding cDNA can then be isolated by avariety of methods, such as by probing with a complete or partial humancDNA or with one or more sets of degenerate probes based on thedisclosed sequences. A cDNA can also be cloned using the polymerasechain reaction, or PCR (Mullis, U.S. Pat. No. 4,683,202), using primersdesigned from the sequences disclosed herein. Within an additionalmethod, the cDNA library can be used to transform or transfect hostcells, and expression of the cDNA of interest can be detected with anantibody to zsig33 Similar techniques can also be applied to theisolation of genomic clones.

Those skilled in the art will recognize that the sequences disclosed inSEQ ID NO: 1, and polypeptide encoded thereby, represent a single alleleof the human zsig33 gene and polypeptide, and that allelic variation andalternative splicing are expected to occur. Allelic variants can becloned by probing cDNA or genomic libraries from different individualsaccording to standard procedures. Allelic variants of the DNA sequenceshown in SEQ ID NO: 1, including those containing silent mutations andthose in which mutations result in amino acid sequence changes, arewithin the scope of the present invention, as are proteins which are theproduct of allelic variation of SEQ ID NO: 2.

The present invention also provides isolated zsig33 polypeptides thatare substantially homologous to the polypeptides of SEQ ID NO: 2 andtheir orthologs. The term “substantially homologous” is used herein todenote polypeptides having 50%, preferably 60%, more preferably at least80%, sequence identity to the sequences shown in SEQ ID NO: 2 or theirorthologs. Such polypeptides will more preferably be at least 90%identical, and most preferably 95% or more identical to SEQ ID NO: 2 orits orthologs. Percent sequence identity is determined by conventionalmethods. See, for example, Altschul et al., Bull. Math. Bio. 48:603-616,1986 and Henikoff and Henikoff, Proc. Natl. Acad. Sci. USA89:10915-10919, 1992. Briefly, two amino acid sequences are aligned tooptimize the alignment scores using a gap opening penalty of 10, a gapextension penalty of 1, and the “blosum 62” scoring matrix of Henikoffand Henikoff (ibid.) as shown in Table 3 (amino acids are indicated bythe standard one-letter codes).

TABLE 3 A R N D C Q E G H I L K M F P S T W Y V A 4 R −1 5 N −2 0 6 D −2−2 1 6 C 0 −3 −3 −3 9 Q −1 1 0 0 −3 5 E −1 0 0 2 −4 2 5 G 0 −2 0 −1 −3−2 −2 6 H −2 0 1 −1 −3 0 0 −2 8 I −1 −3 −3 −3 −1 −3 −3 −4 −3 4 L −1 −2−3 −4 −1 −2 −3 −4 −3 2 4 K −1 2 0 −1 −3 1 1 −2 −1 −3 −2 5 M −1 −1 −2 −3−1 0 −2 −3 −2 1 2 −1 5 F −2 −3 −3 −3 −2 −3 −3 −3 −1 0 0 −3 0 6 P −1 −2−2 −1 −3 −1 −1 −2 −2 −3 −3 −1 −2 −4 7 S 1 −1 1 0 −1 0 0 0 −1 −2 −2 0 −1−2 −1 4 T 0 −1 0 −1 −1 −1 −1 −2 −2 −1 −1 −1 −1 −2 −1 1 5 W −3 −3 −4 −4−2 −2 −3 −2 −2 −3 −2 −3 −1 1 −4 −3 −2 11 Y −2 −2 −2 −3 −2 −1 −2 −3 2 −1−1 −2 −1 3 −3 −2 −2 2 7 V 0 −3 −3 −3 −1 −2 −2 −3 −3 3 1 −2 1 −1 −2 −2 0−3 −1 4

-   -   The percent identity is then calculated as:        $\frac{{Total}\quad{number}\quad{of}\quad{identical}\quad{matches}}{\begin{matrix}        \left\lbrack {{length}\quad{of}\quad{the}\quad{longer}\quad{sequence}\quad{plus}\quad{the}\quad{number}} \right. \\        {{of}\quad{gaps}\quad{introduced}\quad{into}\quad{the}\quad{longer}\quad{sequence}\quad{in}} \\        \left. {{order}\quad{to}\quad{align}\quad{the}\quad{two}\quad{sequences}} \right\rbrack        \end{matrix}} \times 100$

Sequence identity of polynucleotide molecules is determined by similarmethods using a ratio as disclosed above.

Substantially homologous proteins and polypeptides are characterized ashaving one or more amino acid substitutions, deletions or additions.These changes are preferably of a minor nature, that is conservativeamino acid substitutions (see Table 4) and other substitutions that donot significantly affect the folding or activity of the protein orpolypeptide; small deletions, typically of one to about 30 amino acids;and small amino- or carboxyl-terminal extensions, such as anamino-terminal methionine residue, a small linker peptide of up to about20-25 residues, or a small extension that facilitates purification (anaffinity tag), such as a polyhistidine tract, protein A (Nilsson et al.,EMBO J. 4:1075, 1985; Nilsson et al., Methods Enzymol. 198:3, 1991),glutathione S transferase (Smith and Johnson, Gene 67:31, 1988), maltosebinding protein (Kellerman and Ferenci, Methods Enzymol. 90:459-463,1982; Guan et al., Gene 67:21-30, 1987), thioredoxin, ubiquitin,cellulose binding protein, T7 polymerase, or other antigenic epitope orbinding domain. See, in general Ford et al., Protein Expression andPurification 2: 95-107, 1991, which is incorporated herein by reference.DNAs encoding affinity tags are available from commercial suppliers(e.g., Pharmacia Biotech, Piscataway, N.J.; New England Biolabs,Beverly, Mass.).

TABLE 4 Conservative amino acid substitutions Basic: arginine lysinehistidine Acidic: glutamic acid aspartic acid polar: glutamineasparagine Hydrophobic: leucine isoleucine valine Aromatic:phenylalanine tryptophan tyrosine Small: glycine alanine serinethreonine methionine

In addition to the 20 standard amino acids, non-standard amino acids(such as 4-hydroxyproline, 6-N-methyl lysine, 2-aminoisobutyric acid,isovaline and α-methyl serine) may be substituted for amino acidresidues of zsig33. A limited number of non-conservative amino acids,amino acids that are not encoded by the genetic code, and unnaturalamino acids may be substituted for zsig33 amino acid residues.“Unnatural amino acids” have been modified after protein synthesis,and/or have a chemical structure in their side chain(s) different fromthat of the standard amino acids. Unnatural amino acids can bechemically synthesized, or preferably, are commercially available, andinclude pipecolic acid, thiazolidine carboxylic acid, dehydroproline, 3-and 4-methylproline, and 3,3-dimethylproline.

Essential amino acids in the zsig33 polypeptides of the presentinvention can be identified according to procedures known in the art,such as site-directed mutagenesis or alanine-scanning mutagenesis(Cunningham and Wells, Science 244:1081-1085, 1989). In the lattertechnique, single alanine mutations are introduced at every residue inthe molecule, and the resultant mutant molecules are tested forbiological activity (e.g., stimulation of gastrointestinal cellcontractility, modulation of nutrient uptake and/or secretion ofdigestive enzymes) to identify amino acid residues that are critical tothe activity of the molecule. See also, Hilton et al., J. Biol. Chem.271:4699-4708, 1996. Sites of ligand-receptor interaction can also bedetermined by physical analysis of structure, as determined by suchtechniques as nuclear magnetic resonance, crystallography, electrondiffraction or photoaffinity labeling, in conjunction with mutation ofputative contact site amino acids. See, for example, de Vos et al.,Science 255:306-312, 1992; Smith et al., J. Mol. Biol. 224:899-904,1992; Wlodaver et al., FEBS Lett. 309:59-64, 1992. The identities ofessential amino acids can also be inferred from analysis of homologieswith related members of the glucagon-secretin family of gut-brainpeptide hormones.

Multiple amino acid substitutions can be made and tested using knownmethods of mutagenesis and screening, such as those disclosed byReidhaar-Olson and Sauer. (Science 241:53-57, 1988) or Bowie and Sauer(Proc. Natl. Acad. Sci. USA 86:2152-2156, 1989). Briefly, these authorsdisclose methods for simultaneously randomizing two or more positions ina polypeptide, selecting for functional polypeptide, and then sequencingthe mutagenized polypeptides to determine the spectrum of allowablesubstitutions at each position. Other methods that can be used includephage display (e.g., Lowman et al., Biochem. 30:10832-10837, 1991;Ladner et al., U.S. Pat. No. 5,223,409; Huse, WIPO Publication WO92/06204) and region-directed mutagenesis (Derbyshire et al., Gene46:145, 1986; Ner et al., DNA 7:127, 1988).

Mutagenesis methods as disclosed above can be combined withhigh-throughput, automated screening methods to detect activity ofcloned, mutagenized polypeptides in host cells. Mutagenized DNAmolecules that encode active polypeptides (e.g., stimulation ofgastrointestinal cell contractility, modulation of nutrient uptakeand/or secretion of digestive enzymes) can be recovered from the hostcells and rapidly sequenced using modern equipment. These methods allowthe rapid determination of the importance of individual amino acidresidues in a polypeptide of interest, and can be applied topolypeptides of unknown structure.

Using the methods discussed above, one of ordinary skill in the art canidentify and/or prepare a variety of polypeptides that are substantiallyhomologous to residues 24 to 37 of SEQ ID NO: 2 or allelic variantsthereof and retain properties of the wild-type protein. Suchpolypeptides may also include additional polypeptide segments asgenerally disclosed above.

The polypeptides of the present invention, including full-lengthproteins and fragments thereof, can be produced in geneticallyengineered host cells according to conventional techniques. Suitablehost cells are those cell types that can be transformed or transfectedwith exogenous DNA and grown in culture, and include bacteria, fungalcells, and cultured higher eukaryotic cells. Eukaryotic cells,particularly cultured cells of multicellular organisms, are preferred.Techniques for manipulating cloned DNA molecules and introducingexogenous DNA into a variety of host cells are disclosed by Sambrook etal., Molecular Cloning: A Laboratory Manual, 2nd ed., Cold Spring HarborLaboratory Press, Cold Spring Harbor, N.Y., 1989, and Ausubel et al.(eds.), Current Protocols in Molecular Biology, John Wiley and Sons,Inc., NY, 1987, which are incorporated herein by reference.

In general, a DNA sequence encoding a zsig33 polypeptide of the presentinvention is operably linked to other genetic elements required for itsexpression, generally including a transcription promoter and terminatorwithin an expression vector. The vector will also commonly contain oneor more selectable markers and one or more origins of replication,although those skilled in the art will recognize that within certainsystems selectable markers may be provided on separate vectors, andreplication of the exogenous DNA may be provided by integration into thehost cell genome. Selection of promoters, terminators, selectablemarkers, vectors and other elements is a matter of routine design withinthe level of ordinary skill in the art. Many such elements are describedin the literature and are available through commercial suppliers.

To direct a zsig33 polypeptide into the secretory pathway of a hostcell, a secretory signal sequence (also known as a leader sequence,prepro sequence or pre sequence) is provided in the expression vector.The secretory signal sequence may be that of the zsig33 polypeptide, ormay be derived from another secreted protein (e.g., t-PA) or synthesizedde novo. The secretory signal sequence is joined to the zsig33 DNAsequence in the correct reading frame. Secretory signal sequences arecommonly positioned 5′ to the DNA sequence encoding the propeptide ofinterest, although certain signal sequences may be positioned elsewherein the DNA sequence of interest (see, e.g., Welch et al., U.S. Pat. No.5,037,743; Holland et al., U.S. Pat. No. 5,143,830).

Cultured mammalian cells are also preferred hosts within the presentinvention. Methods for introducing exogenous DNA into mammalian hostcells include calcium phosphate-mediated transfection (Wigler et al.,Cell 14:725, 1978; Corsaro and Pearson, Somatic Cell Genetics 7:603,1981: Graham and Van der Eb, Virology 52:456, 1973), electroporation(Neumann et al., EMBO J. 1:841-845, 1982), DEAE-dextran mediatedtransfection (Ausubel et al., eds., Current Protocols in MolecularBiology, John Wiley and Sons, Inc., NY, 1987), liposome-mediatedtransfection (Hawley-Nelson et al., Focus 15:73, 1993; Ciccarone et al.,Focus 15:80, 1993), and viral vectors (A. Miller and G. Rosman,BioTechniques 7:980-90, 1989; Q. Wang and M. Finer, Nature Med.2:714-16, 1996), which are incorporated herein by reference. Theproduction of recombinant polypeptides in cultured mammalian cells isdisclosed, for example, by Levinson et al., U.S. Pat. No. 4,713,339;Hagen et al., U.S. Pat. No. 4,784,950; Palmiter et al., U.S. Pat. No.4,579,821; and Ringold, U.S. Pat. No. 4,656,134, which are incorporatedherein by reference. Preferred cultured mammalian cells include theCOS-1 (ATCC No. CRL 1650), COS-7 (ATCC No. CRL 1651), BHK 570 (ATCC No.CRL 10314), 293 (ATCC No. CRL 1573; Graham et al., J. Gen. Virol.36:59-72, 1977) and Chinese hamster ovary (e.g. CHO-K1; ATCC No. CCL 61)cell lines. Additional suitable cell lines are known in the art andavailable from public depositories such as the American Type CultureCollection, Rockville, Md. In general, strong transcription promotersare preferred, such as promoters from SV-40 or cytomegalovirus. See,e.g., U.S. Pat. No. 4,956,288. Other suitable promoters include thosefrom metallothionein genes (U.S. Pat. Nos. 4,579,821 and 4,601,978,which are incorporated herein by reference) and the adenovirus majorlate promoter.

Drug selection is generally used to select for cultured mammalian cellsinto which foreign DNA has been inserted. Such cells are commonlyreferred to as “transfectants”. Cells that have been cultured in thepresence of the selective agent and are able to pass the gene ofinterest to their progeny are referred to as “stable transfectants.” Apreferred selectable marker is a gene encoding resistance to theantibiotic neomycin. Selection is carried out in the presence of aneomycin-type drug, such as G-418 or the like. Selection systems mayalso be used to increase the expression level of the gene of interest, aprocess referred to as “amplification.” Amplification is carried out byculturing transfectants in the presence of a low level of the selectiveagent and then increasing the amount of selective agent to select forcells that produce high levels of the products of the introduced genes.A preferred amplifiable selectable marker is dihydrofolate reductase,which confers resistance to methotrexate. Other drug resistance genes(e.g., hygromycin resistance, multi-drug resistance, puromycinacetyltransferase) can also be used. Alternative markers that introducean altered phenotype, such as green fluorescent protein, or cell surfaceproteins such as CD4, CD8, Class I MHC, placental alkaline phosphatasemay be used to sort transfected cells from untransfected cells by suchmeans as FACS sorting or magnetic bead separation technology.

Other higher eukaryotic cells can also be used as hosts, including plantcells, insect cells and avian cells. The use of Agrobacterium rhizogenesas a vector for expressing genes in plant cells has been reviewed bySinkar et al., J. Biosci. (Bangalore) 11:47-58, 1987. Transformation ofinsect cells and production of foreign polypeptides therein is disclosedby Guarino et al., U.S. Pat. No. 5,162,222 and WIPO publication WO94/06463. Insect cells can be infected with recombinant baculovirus,commonly derived from Autographa californica nuclear polyhedrosis virus(AcNPV). DNA encoding the zsig33 polypeptide is inserted into thebaculoviral genome in place of the AcNPV polyhedrin gene coding sequenceby one of two methods. The first is the traditional method of homologousDNA recombination between wild-type AcNPV and a transfer vectorcontaining the zsig33 flanked by AcNPV sequences. Suitable insect cells,e.g. SF9 cells, are infected with wild-type AcNPV and transfected with atransfer vector comprising a zsig33 polynucleotide operably linked to anAcNPV polyhedrin gene promoter, terminator, and flanking sequences. See,King, L. A. and Possee, R. D., The Baculovirus Expression System: ALaboratory Guide, London, Chapman & Hall; O'Reilly, D. R. et al.,Baculovirus Expression Vectors: A Laboratory Manual, New York, OxfordUniversity Press., 1994; and, Richardson, C. D., Ed., BaculovirusExpression Protocols, Methods in Molecular Biology, Totowa, N.J., HumanaPress, 1995. Natural recombination within an insect cell will result ina recombinant baculovirus which contains zsig33 driven by the polyhedrinpromoter. Recombinant viral stocks are made by methods commonly used inthe art.

The second method of making recombinant baculovirus utilizes atransposon-based system described by Luckow (Luckow, V. A, et al., JVirol 67:4566-79, 1993). This system is sold in the Bac-to-Bac kit (LifeTechnologies, Rockville, Md.). This system utilizes a transfer vector,pFastBacl™ (Life Technologies) containing a Tn7 transposon to move theDNA encoding the zsig33 polypeptide into a baculovirus genome maintainedin E. coli as a large plasmid called a “bacmid.” The pFastBacl™ transfervector utilizes the AcNPV polyhedrin promoter to drive the expression ofthe gene of interest, in this case zsig33. However, pFastBacl™ can bemodified to a considerable degree. The polyhedrin promoter can beremoved and substituted with the baculovirus basic protein promoter(also known as Pcor, p6.9 or MP promoter) which is expressed earlier inthe baculovirus infection, and has been shown to be advantageous forexpressing secreted proteins. See, Hill-Perkins, M. S. and Possee, R.D., J Gen Virol 71:971-6, 1990; Bonning, B. C. et al., J Gen Virol75:1551-6, 1994; and, Chazenbalk, G. D., and Rapoport, B., J Biol Chem270:1543-9, 1995. In such transfer vector constructs, a short or longversion of the basic protein promoter can be used. Moreover, transfervectors can be constructed which replace the native zsig33 secretorysignal sequences with secretory signal sequences derived from insectproteins. For example, a secretory signal sequence from EcdysteroidGlucosyltransferase (EGT), honey bee Melittin (Invitrogen, Carlsbad,Calif.), or baculovirus gp67 (PharMingen, San Diego, Calif.) can be usedin constructs to replace the native zsig33 secretory signal sequence. Inaddition, transfer vectors can include an in-frame fusion with DNAencoding an epitope tag at the C- or N-terminus of the expressed zsig33polypeptide, for example, a Glu—Glu epitope tag (Grussenmeyer, T. etal., Proc Natl Acad. Sci. 82:7952-4, 1985). Using a technique known inthe art, a transfer vector containing zsig33 is transformed into E.Coli, and screened for bacmids which contain an interrupted lacZ geneindicative of recombinant baculovirus. The bacmid DNA containing therecombinant baculovirus genome is isolated, using common techniques, andused to transfect Spodoptera frugiperda cells, e.g. Sf9 cells.Recombinant virus that expresses zsig33 is subsequently produced.Recombinant viral stocks are made by methods commonly used the art.

The recombinant virus is used to infect host cells, typically a cellline derived from the fall armyworm, Spodoptera frugiperda. See, ingeneral, Glick and Pasternak, Molecular Biotechnology: Principles andApplications of Recombinant DNA, ASM Press, Washington, D.C., 1994.Another suitable cell line is the High FiveO™ cell line (Invitrogen)derived from Trichoplusia ni (U.S. Pat. No. 5,300,435). Commerciallyavailable serum-free media are used to grow and maintain the cells.Suitable media are Sf900 II™ (Life Technologies) or ESF 921™ (ExpressionSystems) for the Sf9 cells; and Ex-cellO405™ (JRH Biosciences, Lenexa,Kans.) or Express FiveO™ (Life Technologies) for the T. ni cells. Thecells are grown up from an inoculation density of approximately 2-5×10⁵cells to a density of 1-2×10⁶ cells at which time a recombinant viralstock is added at a multiplicity of infection (MOI) of 0.1 to 10, moretypically near 3. The recombinant virus-infected cells typically producethe recombinant zsig33 polypeptide at 12-72 hours post-infection andsecrete it with varying efficiency into the medium. The culture isusually harvested 48 hours post-infection. Centrifugation is used toseparate the cells from the medium (supernatant). The supernatantcontaining the zsig33 polypeptide is filtered through micropore filters,usually 0.45 μm pore size. Procedures used are generally described inavailable laboratory manuals (King, L. A. and Possee, R. D., ibid.;O'Reilly, D. R. et al., ibid.; Richardson, C. D., ibid.). Subsequentpurification of the zsig33 polypeptide from the supernatant can beachieved using methods described herein.

Fungal cells, including yeast cells, and particularly cells of thegenera Saccharomyces and Pichia, can also be used within the presentinvention, such as for producing zsig33 fragments or polypeptidefusions. Methods for transforming yeast cells with exogenous DNA andproducing recombinant polypeptides therefrom are disclosed by, forexample, Kawasaki, U.S. Pat. No. 4,599,311; Kawasaki et al., U.S. Pat.No. 4,931,373; Brake, U.S. Pat. No. 4,870,008; Welch et al., U.S. Pat.No. 5,037,743; and Murray et al., U.S. Pat. No. 4,845,075, which areincorporated herein by reference. Transformed cells are selected byphenotype determined by the selectable marker, commonly drug resistanceor the ability to grow in the absence of a particular nutrient (e.g.,leucine). A preferred vector system for use in yeast is the POT1 vectorsystem disclosed by Kawasaki et al. (U.S. Pat. No. 4,931,373), whichallows transformed cells to be selected by growth in glucose-containingmedia. Suitable promoters and terminators for use in yeast include thosefrom glycolytic enzyme genes (see, e.g., Kawasaki, U.S. Pat. No.4,599,311; Kingsman et al., U.S. Pat. No. 4,615,974; and Bitter, U.S.Pat. No. 4,977,092, which are incorporated herein by reference) andalcohol dehydrogenase genes. See also U.S. Pat. Nos. 4,990,446;5,063,154; 5,139,936 and 4,661,454, which are incorporated herein byreference. Transformation systems for other yeasts, including Hansenulapolymorpha, Schizosaccharomyces pombe, Kluyveromyces lactis,Kluyveromyces fragilis, Ustilago maydis, Pichia pastoris, Pichiaguillermondii, Pichia methanolica and Candida maltosa are known in theart. See, for example, Gleeson et al., J. Gen. Microbiol. 132:3459-3465,1986 and Cregg, U.S. Pat. No. 4,882,279. Aspergillus cells may beutilized according to the methods of McKnight et al., U.S. Pat. No.4,935,349, which is incorporated herein by reference. Methods fortransforming Acremonium chrysogenum are disclosed by Sumino et al., U.S.Pat. No. 5,162,228, which is incorporated herein by reference. Methodsfor transforming Neurospora are disclosed by Lambowitz, U.S. Pat. No.4,486,533, which is incorporated herein by reference.

Transformed or transfected host cells are cultured according toconventional procedures in a culture medium containing nutrients andother components required for the growth of the chosen host cells. Avariety of suitable media, including defined media and complex media,are known in the art and generally include a carbon source, a nitrogensource, essential amino acids, vitamins and minerals. Media may alsocontain such components as growth factors or serum, as required. Thegrowth medium will generally select for cells containing the exogenouslyadded DNA by, for example, drug selection or deficiency in an essentialnutrient which is complemented by the selectable marker carried on theexpression vector or co-transfected into the host cell. P. methanolicacells are cultured in a medium comprising adequate sources of carbon,nitrogen and trace nutrients at a temperature of about 25° C. to 35° C.Liquid cultures are provided with sufficient aeration by conventionalmeans, such as shaking of small flasks or sparging of fermentors. Apreferred culture medium for P. methanolica is YEPD (2% D-glucose, 2%Bacto™ Peptone (Difco Laboratories, Detroit, Mich.), 1% Bacto™ yeastextract (Difco Laboratories), 0.004% adenine and 0.006% L-leucine).

Expressed recombinant zsig33 polypeptides can be purified usingfractionation and/or conventional purification methods and media.Ammonium sulfate precipitation and acid or chaotrope extraction may beused for fractionation of samples. Exemplary purification steps mayinclude hydroxyapatite, size exclusion, FPLC and reverse-phase highperformance liquid chromatography. Suitable anion exchange media includederivatized dextrans, agarose, cellulose, polyacrylamide, specialtysilicas, and the like. PEI, DEAE, QAE and Q derivatives are preferred,with DEAE Fast-Flow Sepharose (Pharmacia, Piscataway, N.J.) beingparticularly preferred. Exemplary chromatographic media include thosemedia derivatized with phenyl, butyl, or octyl groups, such asPhenyl-Sepharose FF (Pharmacia), Toyopearl butyl 650 (Toso Haas,Montgomeryville, Pa.), Octyl-Sepharose (Pharmacia) and the like; orpolyacrylic resins, such as Amberchrom CG 71 (Toso Haas) and the like.Suitable solid supports include glass beads, silica-based resins,cellulosic resins, agarose beads, cross-linked agarose beads,polystyrene beads, cross-linked polyacrylamide resins and the like thatare insoluble under the conditions in which they are to be used. Thesesupports may be modified with reactive groups that allow attachment ofproteins by amino groups, carboxyl groups, sulfhydryl groups, hydroxylgroups and/or carbohydrate moieties. Examples of coupling chemistriesinclude cyanogen bromide activation, N-hydroxysuccinimide activation,epoxide activation, sulfhydryl activation, hydrazide activation, andcarboxyl and amino derivatives for carbodiimide coupling chemistries.These and other solid media are well known and widely used in the art,and are available from commercial suppliers. Methods for bindingreceptor polypeptides to support media are well known in the art.Selection of a particular method is a matter of routine design and isdetermined in part by the properties of the chosen support. See, forexample, Affinity Chromatography: Principles & Methods, Pharmacia LKBBiotechnology, Uppsala, Sweden, 1988.

The polypeptides of the present invention can be isolated byexploitation of small size and low pI. For example, polypeptides of thepresent invention can be bound to anionic exchanges at low pH values.Other methods of purification include purification of glycosylatedproteins by lectin affinity chromatography and ion exchangechromatography (Methods in Enzmmol., Vol. 182, “Guide to ProteinPurification”, M. Deutscher, (ed.), Acad. Press, San Diego, 1990, pp.529-39). Alternatively, a fusion of the polypeptide of interest and anaffinity tag (e.g., polyhistidine, maltose-binding protein, animmunoglobulin domain) may be constructed to facilitate purification.

Protein refolding (and optionally reoxidation) procedures may beadvantageously used. It is preferred to purify the protein to >80%purity, more preferably to >90% purity, even more preferably >95%, andparticularly preferred is a pharmaceutically pure state, that is greaterthan 99.9% pure with respect to contaminating macromolecules,particularly other proteins and nucleic acids, and free of infectiousand pyrogenic agents. Preferably, a purified protein is substantiallyfree of other proteins, particularly other proteins of animal origin.

zsig33 polypeptides or fragments thereof may also be prepared throughchemical synthesis. zsig33 polypeptides may be monomers or multimers;glycosylated or non-glycosylated; pegylated or non-pegylated; amidatedor non-amidated; sulfated or non-sulfated; and may or may not include aninitial methionine amino acid residue. For example, zsig33 polypeptidescan also be synthesized by exclusive solid phase synthesis, partialsolid phase methods, fragment condensation or classical solutionsynthesis. The polypeptides are preferably prepared by solid phasepeptide synthesis, for example as described by Merrifield, J. Am. Chem.Soc. 85:2149, 1963. The synthesis is carried out with amino acids thatare protected at the alpha-amino terminus. Trifunctional amino acidswith labile side-chains are also protected with suitable groups toprevent undesired chemical reactions from occurring during the assemblyof the polypeptides. The alpha-amino protecting group is selectivelyremoved to allow subsequent reaction to take place at theamino-terminus. The conditions for the removal of the alpha-aminoprotecting group do not remove the side-chain protecting groups.

The alpha-amino protecting groups are those known to be useful in theart of stepwise polypeptide synthesis. Included are acyl type protectinggroups (e.g., formyl, trifluoroacetyl, acetyl), aryl type protectinggroups (e.g.; biotinyl), aromatic urethane type protecting groups [e.g.,benzyloxycarbonyl (Cbz), substituted benzyloxycarbonyl and9-fluorenylmethyloxycarbonyl (Fmoc)], aliphatic urethane protectinggroups [e.g., t-butyloxycarbonyl (tBoc), isopropyloxycarbonyl,cyclohexloxycarbonyl] and alkyl type protecting groups (e.g., benzyl,triphenylmethyl). The preferred protecting groups are tBoc and Fmoc.

The side-chain protecting groups selected must remain intact duringcoupling and not be removed during the deprotection of theamino-terminus protecting group or during coupling conditions. Theside-chain protecting groups must also be removable upon the completionof synthesis using reaction conditions that will not alter the finishedpolypeptide. In tBoc chemistry, the side-chain protecting groups fortrifunctional amino acids are mostly benzyl based. In Fmoc chemistry,they are mostly tert-butyl or trityl based.

In tBoc chemistry, the preferred side-chain protecting groups are tosylfor arginine, cyclohexyl for aspartic acid, 4-methylbenzyl (andacetamidomethyl) for cysteine, benzyl for glutamic acid, serine andthreonine, benzyloxymethyl (and dinitrophenyl) for histidine,2-Cl-benzyloxycarbonyl for lysine, formyl for tryptophan and2-bromobenzyl for tyrosine. In Fmoc chemistry, the preferred side-chainprotecting groups are 2,2,5,7,8-pentamethylchroman-6-sulfonyl (Pmc) or2,2,4,6,7-pentamethyldihydrobenzofuran-5-sulfonyl (Pbf) for arginine,trityl for asparagine, cysteine, glutamine and histidine, tert-butyl foraspartic acid, glutamic acid, serine, threonine and tyrosine, tBoc forlysine and tryptophan.

For the synthesis of phosphopeptides, either direct or post-assemblyincorporation of the phosphate group is used. In the directincorporation strategy, the phosphate group on serine, threonine ortyrosine may be protected by methyl, benzyl, or tert-butyl in Fmocchemistry or by methyl, benzyl or phenyl in tBoc chemistry. Directincorporation of phosphotyrosine without phosphate protection can alsobe used in Fmoc chemistry. In the post-assembly incorporation strategy,the unprotected hydroxyl groups of serine, threonine or tyrosine arederivatized on solid phase with di-tert-butyl-, dibenzyl- ordimethyl-N,N′-diisopropylphosphoramidite and then oxidized bytert-butylhydroperoxide.

Solid phase synthesis is usually carried out from the carboxyl-terminusby coupling the alpha-amino protected (side-chain protected) amino acidto a suitable solid support. An ester linkage is formed when theattachment is made to a chloromethyl, chlortrityl or hydroxymethylresin, and the resulting polypeptide will have a free carboxyl group atthe C-terminus. Alternatively, when an amide resin such asbenzhydrylamine or p-methylbenzhydrylamine resin (for tBoc chemistry)and Rink amide or PAL resin (for Fmoc chemistry) are used, an amide bondis formed and the resulting polypeptide will have a carboxamide group atthe C-terminus. These resins, whether polystyrene- or polyamide-based orpolyethyleneglycol-grafted, with or without a handle or linker, with orwithout the first amino acid attached, are commercially available, andtheir preparations have been described by Stewart et al., “Solid PhasePeptide Synthesis” (2nd Edition), (Pierce Chemical Co., Rockford, Ill.,1984) and Bayer & Rapp Chem. Pept. Prot. 3:3 (1986); and Atherton etal., Solid Phase Peptide Synthesis: A Practical Approach, IRL Press,Oxford, 1989.

The C-terminal amino acid, protected at the side chain if necessary, andat the alpha-amino group, is attached to a hydroxylmethyl resin usingvarious activating agents including dicyclohexylcarbodiimide (DCC),N,N′-diisopropylcarbodiimide (DIPCDI) and carbonyldiimidazole (CDI). Itcan be attached to chloromethyl or chlorotrityl resin directly in itscesium tetramethylammonium salt form or in the presence of triethylamine(TEA) or diisopropylethylamine (DIEA). First amino acid attachment to anamide resin is the same as amide bond formation during couplingreactions.

Following the attachment to the resin support, the alpha-aminoprotecting group is removed using various reagents depending on theprotecting chemistry (e.g., tBoc, Fmoc). The extent of Fmoc removal canbe monitored at 300-320 nm or by a conductivity cell. After removal ofthe alpha-amino protecting group, the remaining protected amino acidsare coupled stepwise in the required order to obtain the desiredsequence.

Various activating agents can be used for the coupling reactionsincluding DCC, DIPCDI, 2-chloro-1,3-dimethylimidium hexafluorophosphate(CIP), benzotriazol-1-yl-oxy-tris-(dimethylamino)-phosphoniumhexafluorophosphate (BOP) and its pyrrolidine analog (PyBOP),bromo-tris-pyrrolidino-phosphonium hexafluorophosphate (PyBroP),O-(benzotriazol-1-yl)-1,1,3,3-tetramethyl-uronium hexafluorophosphate(HATU) and its tetrafluoroborate analog (TBTU) or its pyrrolidine analog(HBPyU), 0-(7-azabenzotriazol-1-yl)-1,1,3,3-tetramethyl-uroniumhexafluorophosphate (HATU) and its tetrafluoroborate analog (TATU) orits pyrrolidine analog (HAPyU). The most common catalytic additives usedin coupling reactions include 4-dimethylaminopyridine (DMAP),3-hydroxy-3,4-dihydro-4-oxo-1,2,3-benzotriazine (HODhbt),N-hydroxybenzotriazole (HOBt) and 1-hydroxy-7-azabenzotriazole (HOAt).Each protected amino acid is used in excess (>2.0 equivalents), and thecouplings are usually carried out in N-methylpyrrolidone (NMP) or inDMF, CH2Cl2 or mixtures thereof. The extent of completion of thecoupling reaction can be monitored at each stage, e.g., by the ninhydrinreaction as described by Kaiser et al., Anal. Biochem. 34:595, 1970.

After the entire assembly of the desired peptide, the peptide-resin iscleaved with a reagent with proper scavengers. The Fmoc peptides areusually cleaved and deprotected by TFA with scavengers (e.g., H₂O,ethanedithiol, phenol and thioanisole). The tBoc peptides are usuallycleaved and deprotected with liquid HF for 1-2 hours at −5 to 0° C.,which cleaves the polypeptide from the resin and removes most of theside-chain protecting groups. Scavengers such as anisole,dimethylsulfide and p-thiocresol are usually used with the liquid HF toprevent cations formed during the cleavage from alkylating and acylatingthe amino acid residues present in the polypeptide. The formyl group oftryptophan and the dinitrophenyl group of histidine need to be removed,respectively by piperidine and thiophenyl in DMF prior to the HFcleavage; The acetamidomethyl group of cysteine can be removed bymercury(II)acetate and alternatively by iodine,thallium(III)trifluoroacetate or silver tetrafluoroborate whichsimultaneously oxidize cysteine to cystine. Other strong acids used fortBoc peptide cleavage and deprotection include trifluoromethanesulfonicacid (TFMSA) and trimethylsilyltrifluoroacetate (TMSOTf).

The activity of molecules of the present invention can be measured usinga variety of assays that measure stimulation of gastrointestinal cellcontractility, modulation of nutrient uptake and/or secretion ofdigestive enzymes. Of particular interest are changes in contractilityof smooth muscle cells. For example, the contractile response ofsegments of mammalian duodenum or other gastrointestinal smooth musclestissue (Depoortere et al., J. Gastrointestinal Motility 1:150-159, 1989,incorporated herein by reference). An exemplary in vivo assay uses anultrasonic micrometer to measure the dimensional changes radiallybetween commissures and longiturdinally to the plane of the valve base(Hansen et al., Society of Thoracic Surgeons 60:S384-390, 1995).

Gastric motility is generally measured in the clinical setting as thetime required for gastric emptying and subsequent transit time throughthe gastrointestinal tract. Gastric emptying scans are well known tothose skilled in the art, and briefly, comprise use of an oral contrastagent, such as barium, or a radiolabeled meal. Solids and liquids can bemeasured independently. A test food or liquid is radiolabeled with anisotope (e.g. ^(99m)Tc), and after ingestion or administration, transittime through the gastrointestinal tract and gastric emptying aremeasured by visualization using gamma cameras (Meyer et al., Am. J. Dig.Dis. 21:296, 1976; Collins et al., Gut 24:1117, 1983; Maughan et al.,Diabet. Med. 13 9 Supp. 5:S6-10, 1996 and Horowitz et al., Arch. Intern.Med. 145:1467-1472, 1985). These studies may be performed before andafter the administration of a promotility agent to quantify the efficacyof the drug.

Assays measuring zsig33 polypeptides ability to affect cellproliferation or differentiation are well known in the art. For example,assays measuring proliferation include such assays as chemosensitivityto neutral red dye (Cavanaugh et al., Investigational New Drugs8:347-354, 1990, incorporated herein by reference), incorporation ofradiolabelled nucleotides (Cook et al., Analytical Biochem. 179:1-7,1989, incorporated herein by reference), incorporation of5-bromo-2′-deoxyuridine (BrdU) in the DNA of proliferating cells(Porstmann et al., J. Immunol. Methods 82:169-179, 1985, incorporatedherein by reference), and use of tetrazolium salts (Mosmann, J. Immunol.Methods 65:55-63, 1983; Alley et al., Cancer Res. 48:589-601, 1988;Marshall et al., Growth Reg. 5:69-84, 1995; and Scudiero et al., CancerRes. 48:4827-4833, 1988; all incorporated herein by reference). Assaysmeasuring differentiation include, for example, measuring cell-surfacemarkers associated with stage-specific expression of a tissue, enzymaticactivity, functional activity or morphological changes (Watt, FASEB,5:281-284, 1991; Francis, Differentiation 57:63-75, 1994; Raes, Adv.Anim. Cell Biol. Technol. Bioprocesses, 161-171, 1989; all incorporatedherein by reference).

Assays can be used to measure other cellular responses, that include,chemotaxis, adhesion, changes in ion channel influx, regulation ofsecond messenger levels and neurotransmitter release. Such assays arewell known in the art. See, for example, in “Basic & ClinicalEndocrinology Ser., Vol. Vol. 3,” Cytochemical Bioassays: Techniques &Applications, Chayen; Chayen, Bitensky, eds., Dekker, New York, 1983.

In view of the tissue distribution observed for zsig33, agonists(including the natural ligand/substrate/cofactor/etc.) and antagonistshave enormous potential in both in vitro and in vivo applications.Compounds identified as zsig33 agonists are useful for promotingstimulation of gastrointestinal cell contractility, modulation ofnutrient uptake and/or secretion of digestive enzymes in vivo and invitro. For example, agonist compounds are useful as components ofdefined cell culture media and regulate the uptake of nutrients, andthus are useful in specifically promoting the growth and/or developmentof gastrointestinal cells such as G cells, enterochromaffin cells andthe epithelial mucosa of the stomach, duodenum, proximal jejunum, antrumand fundus.

The family of gut-brain peptides has been associated with neurologicaland CNS functions. For example, NPY, a peptide with receptors in boththe brain and the gut has been shown to stimulate appetite whenadministered to the central nervous system (Gehlert, Life Sciences55(6):551-562, 1994). Motilin immunoreactivity has been identified indifferent regions of the brain, particularly the cerebellum, and in thepituitary (Gasparini et al., Hum. Genetics 94(6):671-674, 1994). Motilinhas been found to coexist with neurotransmitter Y-aminobutyric acid incerebellum (Chan-Patay, Proc. Sym. 50th Anniv. Meet. Br. Pharmalog.Soc.:1-24, 1982). Physiological studies have provided some evidence thatmotilin has an affect on feeding behavior (Rosenfield et al., Phys.Behav. 39(6):735-736, 1987), bladder control, pituitary growth hormonerelease. Other gut-brain peptides, such as CCK, enkephalin, VIP andsecretin have been shown to be involved in control of blood pressure,heart rate, behavior, and pain modulation, in addition to be active inthe digestive system. Therefore, zsig33, or some portion thereof, couldbe expected to have some neurological association.

Using site-specific changes in the amino acid and DNA sequences of thepresent invention analogs can be made that are either antagonists,agonists or partial agonists (Maculay et al., Peptides: Chem. Struct.Biol. pp. 659, 1996). Antagonists are useful for clinical conditionsassociated with gastrointestinal hypermotility such as diarrhea andCrohn's disease. Antagonists are also useful as research reagents forcharacterizing sites of ligand-receptor interaction.

A zsig33 ligand-binding polypeptide can also be used for purification ofligand. The polypeptide is immobilized on a solid support, such as beadsof agarose, cross-linked agarose, glass, cellulosic resins, silica-basedresins, polystyrene, cross-linked polyacrylamide, or like materials thatare stable under the conditions of use. Methods for linking polypeptidesto solid supports are known in the art, and include amine chemistry,cyanogen bromide activation, N-hydroxysuccinimide activation, epoxideactivation, sulfhydryl activation, and hydrazide activation. Theresulting medium will generally be configured in the form of a column,and fluids containing ligand are passed through the column one or moretimes to allow ligand to bind to the receptor polypeptide. The ligand isthen eluted using changes in salt concentration, chaotropic agents(guanidine HCl), or pH to disrupt ligand-receptor binding.

An assay system that uses a ligand-binding receptor (or an antibody, onemember of a complement/anti-complement pair) or a binding fragmentthereof, and a commercially available biosensor instrument (BIAcore™,Pharmacia Biosensor, Piscataway, N.J.) may be advantageously employed.Such receptor, antibody, member of a complement/anti-complement pair orfragment is immobilized onto the surface of a receptor chip. Use of thisinstrument is disclosed by Karlsson, J. Immunol. Methods 145:229-40,1991 and Cunningham and Wells, J. Mol. Biol. 234:554-63, 1993. Areceptor, antibody, member or fragment is covalently attached, usingamine or sulfhydryl chemistry, to dextran fibers that are attached togold film within the flow cell. A test sample is passed through thecell. If a ligand, epitope, or opposite member of thecomplement/anti-complement pair is present in the sample, it will bindto the immobilized receptor, antibody or member, respectively, causing achange in the refractive index of the medium, which is detected as achange in surface plasmon resonance of the gold film. This system allowsthe determination of on- and off-rates, from which binding affinity canbe calculated, and assessment of stoichiometry of binding.

Ligand-binding receptor polypeptides can also be used within other assaysystems known in the art. Such systems include Scatchard analysis fordetermination of binding affinity (see Scatchard, Ann. NY Acad. Sci. 51:660-72, 1949) and calorimetric assays (Cunningham et al., Science253:545-48, 1991; Cunningham et al., Science 245:821-25, 1991).

zsig33 polypeptides can also be used to prepare antibodies thatspecifically bind to zsig33 epitopes, peptides or polypeptides. Methodsfor preparing polyclonal and monoclonal antibodies are well known in theart (see, for example, Sambrook et al., Molecular Cloning: A LaboratoryManual, Second Edition, Cold Spring Harbor, N.Y., 1989; and Hurrell, J.G. R., Ed., Monoclonal Hybridoma Antibodies: Techniques andApplications, CRC Press, Inc., Boca Raton, Fla., 1982, which areincorporated herein by reference). As would be evident to one ofordinary skill in the art, polyclonal antibodies can be generated from avariety of warm-blooded animals, such as horses, cows, goats, sheep,dogs, chickens, rabbits, mice, and rats.

The immunogenicity of a zsig33 polypeptide may be increased through theuse of an adjuvant, such as alum (aluminum hydroxide) or Freund'scomplete or incomplete adjuvant. Polypeptides useful for immunizationalso include fusion polypeptides, such as fusions of zsig33 or a portionthereof with an immunoglobulin polypeptide or with maltose bindingprotein. The polypeptide immunogen may be a full-length molecule or aportion thereof. If the polypeptide portion is “hapten-like”, suchportion may be advantageously joined or linked to a macromolecularcarrier (such as keyhole limpet hemocyanin (KLH), bovine serum albumin(BSA) or tetanus toxoid) for immunization.

As used herein, the term “antibodies” includes polyclonal antibodies,affinity-purified polyclonal antibodies, monoclonal antibodies, andantigen-binding fragments, such as F(ab′)₂ and Fab proteolyticfragments. Genetically engineered intact antibodies or fragments, suchas chimeric antibodies, Fv fragments, single chain antibodies and thelike, as well as synthetic antigen-binding peptides and polypeptides,are also included. Non-human antibodies may be humanized by graftingonly non-human CDRs onto human framework and constant regions, or byincorporating the entire non-human variable domains (optionally“cloaking” them with a human-like surface by replacement of exposedresidues, wherein the result is a “veneered” antibody). In someinstances, humanized antibodies may retain non-human residues within thehuman variable region framework domains to enhance proper bindingcharacteristics. Through humanizing antibodies, biological half-life maybe increased, and the potential for adverse immune reactions uponadministration to humans is reduced. Alternative techniques forgenerating or selecting antibodies useful herein include in vitroexposure of lymphocytes to zsig33 protein or peptide, and selection ofantibody display libraries in phage or similar vectors (for instance,through use of immobilized or labeled zsig33 protein or peptide).

Antibodies are defined to be specifically binding if they bind to azsig33 polypeptide with a binding affinity (K_(a)) of 10⁶ M^(—1) orgreater, preferably 10⁷ M^(—1) or greater, more preferably 10⁸ M^(—1) orgreater, and most preferably 10⁹ M^(—1) or greater. The binding affinityof an antibody can be readily determined by one of ordinary skill in theart (for example, by Scatchard analysis).

A variety of assays known to those skilled in the art can be utilized todetect antibodies which specifically bind to zsig33 proteins orpeptides. Exemplary assays are described in detail in Antibodies: ALaboratory Manual, Harlow and Lane (Eds.), Cold Spring Harbor LaboratoryPress, 1988. Representative examples of such assays include: concurrentimmunoelectrophoresis, radioimmunoassay, radioimmuno-precipitation,enzyme-linked immunosorbent assay (ELISA), dot blot or Western blotassay, inhibition or competition assay, and sandwich assay. In addition,antibodies can be screened for binding to wild-type versus mutant zsig33protein or peptide.

Antibodies to zsig33 may be used for tagging cells that express zsig33for isolating zsig33 by affinity purification; for diagnostic assays fordetermining circulating levels of zsig33 polypeptides; for detecting orquantitating soluble zsig33 as marker of underlying pathology ordisease; in analytical methods employing FACS; for screening expressionlibraries; for generating anti-idiotypic antibodies; and as neutralizingantibodies or as antagonists to block zsig33 activity in vitro and invivo. Suitable direct tags or labels include radionuclides, enzymes,substrates, cofactors, inhibitors, fluorescent markers, chemiluminescentmarkers, magnetic particles and the like; indirect tags or labels mayfeature use of biotin-avidin or other complement/anti-complement pairsas intermediates. Antibodies herein may also be directly or indirectlyconjugated to drugs, toxins, radionuclides and the like, and theseconjugates used for in vivo diagnostic or therapeutic applications.

Molecules of the present invention can be used to identify and isolatereceptors that mediate the function of zsig33. For example, proteins andpeptides of the present invention can be immobilized on a column andmembrane preparations run over the column (Immobilized Affinity LigandTechniques, Hermanson et al., eds., Academic Press, San Diego, Calif.,1992, pp. 195-202). Proteins and peptides can also be radiolabeled(Methods in Enzymol., vol. 182, “Guide to Protein Purification”, M.Deutscher, ed., Acad. Press, San Diego, 1990, 721-737) or photoaffinitylabeled (Brunner et al., Ann. Rev. Biochem. 62:483-514, 1993 and Fedanet al., Biochem. Pharmacol. 33:1167-1180, 1984) and specificcell-surface proteins can be identified.

The polypeptides, nucleic acid and/or antibodies of the presentinvention may be used in treatment of disorders associated withgastrointestinal cell contractility, secretion of digestive enzymes andacids, gastrointestinal motility, recruitment of digestive enzymes;inflammation, particularly as it affects the gastrointestinal system;reflux disease and regulation of nutrient absorption. Specificconditions that will benefit from treatment with molecules of thepresent invention include, but are not limited to, diabeticgastroparesis, post-surgical gastroparesis, vagotomy, chronic idiopathicintestinal pseudo-obstruction and gastroesophageal reflux disease.Additional uses include, gastric emptying for radiological studies,stimulating gallbladder contraction and antrectomy.

The motor and neurological affects of molecules of the present inventionmake it useful for treatment of obesity and other metabolic disorderswhere neurological feedback modulates nutritional absorption. Themolecules of the present invention are useful for regulating satiety,glucose absorption and metabolism, and neuropathy-associatedgastrointestinal disorders.

Molecules of the present invention are also useful as additives toanti-hypoglycemic preparations containing glucose and as adsorptionenhancers for oral drugs which require fast nutrient action.Additionally, molecules of the present invention can be used tostimulate glucose-induced insulin release.

For pharmaceutical use, the proteins of the present invention areformulated for parenteral, nasal inhalation, particularly intravenous orsubcutaneous, delivery according to conventional methods. Intravenousadministration will be by bolus injection or infusion over a typicalperiod of one to several hours. In general, pharmaceutical formulationswill include a zsig33 protein in combination with a pharmaceuticallyacceptable vehicle, such as saline, buffered saline, 5% dextrose inwater or the like. Formulations may further include one or moreexcipients, preservatives, solubilizers, buffering agents, albumin toprevent protein loss on vial surfaces, etc. Methods of formulation arewell known in the art and are disclosed, for example, in Remington'sPharmaceutical Sciences, Gennaro, ed., Mack Publishing Co., Easton Pa.,1990, which is incorporated herein by reference. Therapeutic doses willgenerally be in the range of 0.1 to 100 μg/kg of patient weight per day,preferably 0.5-20 μg/kg per day, with the exact dose determined by theclinician according to accepted standards, taking into account thenature and severity of the condition to be treated, patient traits, etc.Determination of dose is within the level of ordinary skill in the art.The proteins may be administered for acute treatment, over one week orless, often over a period of one to three days or may be used in chronictreatment, over several months or years. For example, a therapeuticallyeffective amount of zsig33 is an amount sufficient to produce aclinically significant change in gastric motility and parameters used tomeasure changes in nutritional absorption. Specific tests for makingsuch measurements are known to these ordinarily skilled in the art.

EXAMPLES Example 1

Scanning of a cDNA database for cDNAs containing a secretion sequencerevealed an expressed sequence tag (EST) that has homology to motilin.The cDNA is from a human fetal pancreatic cDNA library.

Confirmation of the EST sequence was made by sequence analyses of thecDNA from which the EST originated. This cDNA was contained in aplasmid, and was excised using cloning sites. The analyses revealed thatthe cDNA encompassed the entire coding region of the DNA encodingzsig33.

Example 2

Northerns were performed using Human Multiple Tissue Blots and Human RNAMaster dot blots from Clontech (Palo Alto, Calif.). The probe wasapproximately 40 bp oligonucleotide ZC12,494 (SEQ ID NO: 5). The probewas end labeled using T4 Polynucleotide Kinase (Life Technologies, Inc.,Gaithersburg, Md.) and T4 Polynucleotide Kinase Forward Buffer (LifeTechnologies, Inc.). The probe was purified using a NUCTRAP pushcolumns. (Stratagene, La Jolla, Calif.). EXPRESSHYB (Clontech) solutionwas used for prehybridization and as a hybridizing solution for theNorthern blots. Hybridization took place at 42° C., and the blots werewashed in 2×SSC and 0.05% SDS at RT, followed by a wash in 1×SSC and0.1% SDS at 71° C. An approximately 600 bp transcript was observed as astrong signal in stomach, with weaker signals seen in pancreas and smallintestine.

Example 3

Two male Sprague-Dawley rats, approximately 12 weeks old (Harlan,Indianapolis, Ind.) were anesthetized with urethane and their stomachswere exposed through a small abdominal incision. Two 2.4 mm transducingcrystals (Sonometrics, Ontario, Canada) were placed on the antralportion of the stomach such that circular contractions could bemonitored as a change in the distance between the two crystals. Thecrystals were attached with VETBOND TISSUE ADHESIVE (3M, St. Paul,Minn.).

10 μl of 1 μM acetylcholine was applied topically to the stomach betweenthe two crystals, and resulted in a rapid, but transient increase in thedistance between two crystals. 10 μl of norepinephrine (NE) at 1 μMcaused a reduction in the distance between the two crystals. Theamplitude of the NE-induced decrease was approximately 50% of theacetylcholine-induced increase in distance. Both responses weretransient.

A negative control of 10 μl of phosphate buffer solution (PBS) appliedtopically between the crystals had no effect.

A 14 amino acid zsig33 peptide (from amino acid residue 24 (Gly) toamino acid residue 37 (Gln) of SEQ ID NO: 2) was dissolved in PBS) and10 μl was applied topically for a final concentration of 1 μg, 10 μg or100 μg. The zsig33 at 1 μg induced a sustained, rhythmic increase anddecrease in crystal distance. This effect appeared to be dose-dependent,with enhanced responses in both rate and amplitude when of thecontractions 10 μg and 100 μg were tested.

Example 4

Eight female ob/ob mice, approximately 6 weeks old (Jackson Labs, BarHarbor, Me.) were adapted to a 4 hour daily feeding schedule for twoweeks. After two weeks on the feeding schedule, the mice were give 100μg of a 14 amino acid amino zsig33 peptide (from amino acid residue 24(Gly) to amino acid residue 37 (Gln) of SEQ ID NO: 2) in 100 μl sterile0.1% BSA by oral gavage, immediately after their eating period(post-prandially). Thirty minutes later, the mice were challenged orallywith 0.5 ml volume of 25% glucose. Retroorbital bleeds were done todetermine serum glucose levels. Blood was drawn prior to zsig33 dosing,prior to oral glucose challenge, and at 1, 2, 4, and 20 hours followingthe glucose challenge.

When zsig33 peptide was given orally at 100 μg, 30-minutes prior to anoral glucose challenge, an enhanced post-prandial glucose absorption wasseen.

Example 5

zsig33-1, a peptide corresponding to amino acid residue 24 (Gly) toamino acid residue 37 (Gln) of SEQ ID NO: 2, was synthesized by solidphase peptide synthesis using a model 431A Peptide Synthesizer (AppliedBiosystems/Perkin Elmer, Foster City, Calif.). Fmoc-Glutamine resin(0.63 mmol/g; Advanced Chemtech, Louisville, Ky.) was used as theinitial support resin. 1 mmol amino acid cartridges (Anaspec, Inc. SanJose, Calif.) were used for synthesis. A mixture of2(1-Hbenzotriazol-y-yl 1,1,3,3-tetrahmethylhyluroniumhexafluorophosphate (HBTU), 1-hydroxybenzotriazol (HOBt), 2 mN,N-Diisolpropylethylamine, N-Methylpyrrolidone, Dichloromethane (allfrom Applied Biosystems/Perkin Elmer) and piperidine (Aldrich ChemicalCo., St. Louis, Mo.), and used for synthesis reagents.

The Peptide Companion software (Peptides International, Louisville, Ky.)was used to predict the aggregation potential and difficulty level forsynthesis for the zsig33-1 peptide. Synthesis was performed using singlecoupling programs, according to the manufacturer's specifications.

The peptide was cleaved from the solid phase following standard TFAcleavage procedure (according to Peptide Cleavage manual, AppliedBiosystems/Perkin Elmer). Purification of the peptide was done byRP-HPLC using a C18, 10 μm semi-peparative column (Vydac, Hesperial,Calif.). Eluted fractions from the column were collected and analyzedfor correct mass and purity by electrospray mass spectrometry. Two poolsof the eluted material were collected. The mass spectrometry analysisresults indicated that both pools contained the purified form of zsig33with a mass of 1600 Daltons. This was the expected mass, so the poolswere combined, frozen and lyophilized.

Example 6

zsig33 was mapped to chromosome 3 using the commercially available“GeneBridge 4 Radiation Hybrid Panel” (Research Genetics, Inc.,Huntsville, Ala.). The GeneBridge 4 Radiation Hybrid Panel contains DNAsfrom each of 93 radiation hybrid clones, plus two control DNAs (the HFLdonor and the A23 recipient). A publicly available WWW server allowsmapping relative to the Whitehead Institute/MIT Center for GenomeResearch's radiation hybrid map of the human genome (the “WICGR”radiation hybrid map) which was constructed with the GeneBridge 4Radiation Hybrid Panel.

For mapping of zsig33 with the “GeneBridge 4 RH Panel”, 20 μl reactionswere set up in a 96-well microtiter plate (Stratagene, La Jolla, Calif.)and used in a “RoboCycler Gradient 96” thermal cycler (Stratagene). Eachof the 95 PCR reactions consisted of 2 μl 10×KlenTaq PCR reaction buffer(CLONTECH Laboratories, Inc., Palo Alto, Calif.), 1.6 μl dNTPs mix (2.5mM each, Perkin-Elmer, Foster City, Calif.), 1 μl sense primer, 1 μlantisense primer, 2 μl “RediLoad” (Research Genetics, Inc., Huntsville,Ala.), 0.4 μl 50×Advantage KlenTaq Polymerase Mix (ClontechLaboratories, Inc.), 25 ng of DNA from an individual hybrid clone orcontrol and ddH2O for a total volume of 20 μl. The reactions wereoverlaid with an equal amount of mineral oil and sealed. The PCR cyclerconditions were as follows: an initial 1 cycle 5 minute denaturation at95° C., 35 cycles of a 1 minute denaturation at 95° C., 1 minuteannealing at 64° C. and 1.5 minute extension at 72° C., followed by afinal 1 cycle extension of 7 minutes at 72° C. The reactions wereseparated by electrophoresis on a 3% NuSieve GTG agarose gel (FMCBioproducts, Rockland, Me.).

The results showed that zsig33 maps 10.43 cR_(—)3000 from the frameworkmarker AFMA216ZG1 on the WICGR chromosome 3 radiation hybrid map.Proximal and distal framework markers were AFMA216ZGI and D3S1263,respectively. The use of surrounding markers positions zsig33 in the3p26.1 region on the integrated LDB chromosome 3 map (The GeneticLocation Database, University of Southhampton, WWW server.

Example 7

The effect of topically applied zsig33 peptide (amino acid 24 to 37 ofSEQ ID NO: 2) on the transit of phenol red through the stomachs offasted male Sprague-Dawley rats (Harlan, Indianapolis, Ind.) wasevaluated. The rats (6 animals, 8 weeks old) were fasted 24 hrs prior tobeing anesthetized with urethane(0.5 ml/100 grams of 25% solution).After anesthetizing, the animals were orally gavaged with 1 ml of PhenolRed solution (50 mg/ml in 2% methylcellulose solution).

The stomach of each animal was exposed through a small abdominalincision and either 1 μg zsig33 peptide or a 14 amino acid control of ascrambled sequence peptide was applied topically to the stomach fiveminutes following the gavage. The amount of Phenol Red remaining in thestomach was determined by measuring optical density of the extractedstomach contents 30 minutes after the gavage.

The zsig33 peptide reduced the amount of Phenol Red remaining in thestomach by approximately 25% compared to a scrambled peptide, indicatingthat the zsig33 peptide enhanced gastric emptying in these rats.

Example 8

Sixteen female ob/ob mice, 8 weeks old, (Jackson Labs, Bar Harbor, Me.)were adapted to a special 4 hour daily feeding schedule for two weeks.The were fed ad libitum from 7:30-11:30 am daily. After two weeks on thefeeding schedule, the mice were divided into two groups of 8. One groupwas given 1.0 μg/mouse of zsig33-1 (14 amino acid peptide) and the othervehicle (a 14 amino acid scrambled sequence peptide) in 100 μl sterile0.1% BSQA by oral gavage just prior to receiving food, and at the end ofthe 4 hour feeding period. The mice were injected twice daily forfourteen days, during which time food intake and body weight wasmeasured daily. One day 14, immediately after the second oral gavage ofthe zsig33-1 peptide, the mice were challenged orally with an 0.5 mlvolume of 25% glucose. Retro-orbital bleeds were done to determine serumglucose levels immediately prior to administration of the zsig33-1peptide or vehicle (t=30 min.), and also at 0, 1, 2, and 4 hoursfollowing the glucose challenge.

Results indicated that when zsig33-1 given orally at 1 μg/mouse had noaffect on daily body weight or food intake measurements, or on glucoseclearance as determined on day 14.

Example 9

A. Gut Northern Tissue Blot

A Northern blot was prepared using mRNA from the following sources:

-   -   1. RNA from Human Colorectal Andenocarcinoma cell line SW480        (Clontech, Palo Alto, Calif.)    -   2. RNA from human small intestine tissue (Clontech)    -   3. RNA from human stomach tissue (Clontech)    -   4. Human Intestinal Smooth Muscle cell line (Hism; ATCC No.        CRL-1692; American Type Culture Collection, 12301 Parklawn        Drive, Rockville, Md.)    -   5. Normal Human Colon cell line (FHC; ATCC No. CRL-1831;        American Type Culture Collection)    -   6. Human Normal Fetal Small Intestine cell line (FHs74 Int.;        ATCC No. CCL241; American Type Culture Collection).

Total RNAs were isolated from Hism, FHC and FHs74 Int. by acid guanidiummethod (Chomczynski et al., Anal. Biochem. 162:156-159, 1987). ThepolyA⁺ RNAs were selected by eluting total RNA through a column thatretains polyA⁻ RNAs (Aviv et al., Proc. Nat. Acad. Sci. 69:1408-1412,1972). 2 μg of polyA⁺ RNA from each sample was separated out in a 1.5%agarose gel in 2.2 M formaldehyde and phosphate buffer. The RNAs weretransferred onto Nytran membrane (Schleicher and Schuell, Keene, N.H.)in 20×SSC overnight. The blot was treated in the UV Stratalinker 2400(Stratagene, La Jolla, Calif.) at 0.12 Joules. The bolt was then bakedat 80° C. for one hour.

Using the full length cDNA (shown in SEQ ID NO: 1) amplified by PCRapproximately 50 ng of zsig33 DNA and 42.5 μl of water was radiolabeledwith ³²P dCTP using a Rediprime pellet kit (Amersham, Arlington Heights,Ill.) according to the manufacturer's specifications. The blot washybridized in EXPRESSHYB (Clontech) at 55° C. overnight. The blot waswashed at room temp. in 2×SSC and 0.1% SDS, then in 2×SSC and 0.1% SDSat 65° C., and finally at 65° C. in 0.1×SSC and 0.1% SDS. Results showedthat zsig33 hybridized to stomach RNA and not to other RNAs from othertissue origins.

B. Tumor Northern Blot

A Northern Territory™—Human Tumor Panel Blot II (Invitrogen, San Diego,Calif.) and a Northern Territory™—Human Stomach Tumor Panel Blot(Invitrogen) were analyzed for expression patterns of zsig33 RNA.

The Human Tumor Panel Blot contained 20 μg of total RNA per lane and wasrun on a 1% denaturing formaldehyde gel. The blot contained RNA from:esophageal tumor, normal esophagus, stomach tumor, normal stomach, colontumor, normal colon, rectal tumor and normal rectum. The Stomach TumorPanel Blot contained total RNA isolated human and normal tissues of fourseparate donors. 20 μg of RNA was used for each sample lane and thelanes alternated a normal and tumor set from each donor.

Probes that were approximately 40 bp oligonucleotide ZC12,494 (SEQ IDNO: 5) were prepared. The probes were end labeled using T4Polynucleotide Kinase (Life Technologies, Inc., Gaithersburg, Md.) andT4 Polynucleotide Kinase Forward Buffer (Life Technologies, Inc.). Theprobes were purified using a NUCTRAP push columns (Stratagene, La Jolla,Calif.). The tumor blot and the stomach blot were both treated in thesame way. EXPRESSHYB (Clontech) solution was used for prehybridizationand as a hybridizing solution for the Northern blots. Hybridization tookplace at 42° C., and the blots were washed in 0.1×SSC and 0.01%. SDS at60° C., followed by a wash in 0.1×SSC and 0.1% SDS at 70° C. The resultsclearly indicate that zsig33 is exclusively expressed in normal stomachtissue in both the Human Tumor Panel and the Human Stomach Tumor Panel.

From the foregoing, it will be appreciated that, although specificembodiments of the invention have been described herein for purposes ofillustration, various modifications may be made without deviating fromthe spirit and scope of the invention. Accordingly, the invention is notlimited except as by the appended claims.

1. An isolated polynucleotide molecule comprising the nucleotidesequence as shown in SEQ ID NO: 1 from nucleotide 70 to nucleotide 111.2. An isolated polynucleotide molecule comprising the nucleotidesequence as shown in SEQ ID NO: 1 from nucleotide 70 to nucleotide 123.3. An isolated polynucleotide molecule comprising the nucleotidesequence as shown in SEQ ID NO: 1 from nucleotide 70 to nucleotide 351.4. An isolated polynucleotide molecule comprising the nucleotidesequence as shown in SEQ ID NO: 1 from nucleotide 1 to nucleotide 111.5. An isolated polynucleotide molecule comprising the nucleotidesequence as shown in SEQ ID NO: 1 from nucleotide 1 to nucleotide 351.6. The isolated polynucleotide of claim 1, wherein the polynucleotide isDNA.
 7. An expression vector comprising the following operably linkedelements: a transcription promoter; a DNA segment comprising thenucleotide sequence as shown in SEQ ID NO: 1 from nucleotide 70 tonucleotide 111; and a transcription terminator.
 8. A cultured cell intowhich has been introduced an expression vector according to claim 7,wherein said cell expresses the polypeptide encoded by the DNA segment.9. A method of producing a polypeptide comprising: culturing a cell intowhich has been introduced the expression vector according to claim 7,whereby the cell expresses the polypeptide encoded by the DNA segment;and recovering the polypeptide, wherein the polypeptide comprises theamino acid sequence as shown in SEQ ID NO: 2 from residue 24 to residue37.
 10. An isolated polynucleotide encoding a polypeptide, wherein thepolypeptide comprises an amino acid segment, and wherein the amino acidsegment is at least 80% identical to the amino acid sequence as shown inSEQ ID NO:2 from residue 24 to residue 37 and wherein the polypeptidehas an activity selected from the group consisting of: a) stimulatinggastrointestinal cell contractility; b) enhancing post-prandial glucoseabsorption; and c) combinations of a) and b).
 11. The isolatedpolynucleotide according to claim 10 wherein the amino acid segment hasone or more amino acid substitutions.
 12. The isolated polynucleotideaccording to claim 11 wherein the amino acid substitutions areconservative amino acid substitutions.
 13. The isolated polynucleotideaccording to claim 11 wherein the amino acid segment has at least 90%identity to the amino acid sequence as shown in SEQ ID NO:2 from residue24 to residue
 37. 14. The isolated polynucleotide according to claim 10wherein the amino acid segment has at least 90% identity to the aminoacid sequence as shown in SEQ ID NO:2 from residue 24 to residue
 37. 15.An isolated polynucleotide encoding a polypeptide, wherein thepolypeptide comprises an amino acid segment, and wherein the amino acidsegment has at least 80% identity to the amino acid sequence as shown inSEQ ID NO:2 from residue 24 to residue 41 and wherein the polypeptidehas an activity selected from the group consisting of: a) stimulatinggastrointestinal cell contractility; b) enhancing post-prandial glucoseabsorption; and c) combinations of a) and b).
 16. The isolatedpolynucleotide according to claim 15 wherein the amino acid segment hasat least 90% identity to the amino acid sequence as shown in SEQ ID NO:2from residue 24 to residue 41.